In detonating a plurality of blasting charges in a blasting pattern it is generally required that the timing of such detonations be controlled precisely. This is true, for example, in quarry blasting where sequential delays between charges must be controlled within milli-second accuracy. In order to control such timing of charges, signal transmission lines are deployed from a central initiating point to transmit a signal to detonate the individual blasting charges. Normally, these lines consist of one or more main trunk lines connected to a plurality of down lines. Timing of the detonating signal is normally accomplished by using preselected lengths of known transmission lines and/or by delaying the signal, e.g., with a discrete signal delay unit or delay detonator, where necessary.
The manner of connection of the signal transmission lines, for example, between a trunk line and a plurality of down lines, depends on the type of transmission line utilized. Conventional combustable fuses and detonating cords may be connected by directly tying the lines together. Such fuses and cords contain a high energy explosive core that creates a loud noise during signal propagation, which noise is of particular concern to workers and when blasting near populated areas.
Non-destructing transmission tubes may also be utilized to carry a detonating signal in a blasting pattern. The transmission tube may be of the type disclosed in U.S. Pat. No. 4,607,573, often referred to as "shock tube". As used herein, the term "transmission tube" refers to any detonating or deflagrating signal transmission tube or line including a flexible hollow tube, which can carry a detonating or deflagrating signal along its interior, which signal does not destroy the tube. The term "signal" when used in connection with the aforementioned transmission tube is intended to refer to both the detonating shock wave or deflagrating flame front that is transmitted along the interior of the tube by combustion of the reactive substances contained therein. The signal moving through a transmission tube is so quiet that it can be considered "noiseless".
Transmission tubes may be connected in a blasting pattern, for example, as disclosed in U.S. Pat. No. 3,987,732. The connection block described therein holds a pair of transmission tubes in parallel relation to a detonator. The detonator contains a high energy explosive charge which detonates progressively along its length in a linear and directional fashion, thereby transferring detonating energy to the transmission tubes in a uni-directional fashion. The reaction in the transmission tubes generally proceeds in the driven direction, and not in the opposite direction, which uni-directional transmission is of concern in a blast pattern because the improper assembly of a transmission tube in a connector may direct the reaction in the wrong direction thereby to prevent reliable signal transmission to bore hole detonators.
It is a primary object of the invention to provide a low energy blasting initiation system surface connection for reliable non-directional transmission of an initiation signal to remote blasting system elements in a low-noise, time controlled manner;
It is another object of the invention to provide an improved connector block to effect the low energy blasting initiation system surface connection wherein reliable initiation of non-directional signal transmission is initiated in at least one transmission tube by a low energy detonator received in the connector block;
It is a further object of the invention to provide a connector block for easy connection of a plurality of transmission tubes in juxtaposed, energy communicating relationship with the explosive end of the low energy detonator, which connector block is inexpensive and essentially disposable;
It is another object of the invention to provide a low energy blasting initiation system connection having a connector block with a shock absorbent, protective body which minimizes shock initiated detonation of the low energy detonator contained therein and which substantially contains any shrapnel upon initiation of the low energy detonator;
It is a still further object of the invention to provide a low energy blasting initiation system having environmentally impervious component parts for easy assembly under adverse environmental conditions to reliably transmit an initiation signal to remote blasting system elements;
It is another object of the invention to provide an improved method of low-noise time controlled initiation of remote blasting system elements that is reliable under adverse environmental conditions.
Other objects will be in part obvious and in part pointed out in more detail hereinafter.
A better understanding of the objects, advantages, features, properties and relations of the invention will be obtained from the following description and accompanying drawings which set forth certain illustrative embodiments and are indicative of the various ways in which the principles of the invention are employed.